The negative sequelae of treatment for breast cancer are well-known: surgery for breast cancer is disfiguring; radiation can cause fatigue, soreness, and long-term cosmetic changes; and chemotherapy often induces nausea, vomiting, hair loss, bleeding and weight gain. Psychological effects of the treatment are often no less debilitating. Research has shown that aversive psychological reaction develop during treatment, such as anticipatory nausea and anxiety, can persist for many years off- treatment. Other off-treatment symptoms have been documented as well, including: intrusive thoughts, nightmares, avoidant behaviors and impairment in vocational, social and/or sexual functioning. Our preliminary data suggest that more than 50% of breast cancer survivors experience such symptoms even 3 or more years off-treatment Many of these symptoms are subsumed under the diagnosis of Post-Traumatic Stress Disorder (PTSD). Proposed revisions to the PTSD stressor criterion the American Psychiatric Association's working draft of the Diagnostic and Statistical Manual of Mental Disorders W recognize a life-threatening illness such as cancer as a potentially traumatic stressor. Although preliminary data suggest that the prevalence of post-traumatic stress symptoms among cancer patients may be quite high, there have been no published studies in the area Three related studies are proposed to investigate the incidence, etiology and treatment of PTSD symptoms in survivors of breast cancer. Study 1, a naturalistic prospective longitudinal analysis of the development of PTSD symptoms among women treated for breast cancer, will examine patterns and risk factors associated with PTSD symptoms. Study 2 will examine the contribution of classical conditioning factors through a prospective, longitudinal analysis of conditioned responses during adjuvant chemotherapy and an experimental analysis of psychobehavioral and cardiovascular reactivity to stimuli associated with the chemotherapy. Study 3 will involve a randomized clinical trial to evaluate the effectiveness of a cognitive- behavioral intervention (incorporating systematic desensitization and psychoeducation) for reducing PTSD symptoms.